In March last year, after a flight from the Far East, the broadcaster Chris Tarrant suffered a stroke. Since then, he’s become addicted to the wonders of “this extraordinary machine in your head”. Fully recovered from his attack, he reports: “I’ve learned a lot about the brain. I’ve been going to a neuropsychologist. One day she came in with this plastic model of a big, fat, crinkly, porridgy melon. And I went, ‘What!’ I mean, I had no idea. The brain is this most extraordinary, fantastic thing. I did say, ‘Does this make you believe in God?’ And she said, ‘No. But it does make you think.’”
According to an old medical joke, the brain is the only organ in the body to have named itself. It’s a fact: our brains are us. Each one weighs about 1.4kg (3lb). You could hold it in the palm of your hand. But it’s more than just an organ. It’s you, in every sense of the word: your intelligence, demeanour, personality, and consciousness. Oscar Wilde wrote: “It is in the brain that everything takes place. It is in the brain that the poppy is red, that the apple is odorous, that the skylark sings.”
In short, it’s your command centre, your HQ; and one thing is certain. A brain attack is like having an earthquake at the centre of your fragile self. When the brain fails, for whatever reason, the human animal will find itself in extremis. Insults to the brain usually come out of the blue. I was 42 when, overnight, I experienced a right-hemisphere haemorrhagic infarct. Today, memories of my weeks on the front line of ill-health – the aqueous blue blink-blink-blink of the ambulance, the muffled sounds of the intensive care unit and the cement-mixer roar of the MRI chamber – have faded to the texture of an old nightmare. I will, however, never cease to be a veteran of that conflict. Scan my cerebral cortex and you will see a fuzzy grey scar, the size of a thumbnail, indicating where the wound in my brain used to be. This “cerebral lesion” has now become part of that infinitely complex organ in which the neurologists of the National Hospital specialise. Professor Andrew Lees, one of Britain’s leading Parkinson’s specialists, says that below the surface of the brain there are the “100bn tiny nerve cells that make up the grey matter”. Another renowned brain surgeon, Henry Marsh, from St George’s Hospital, London, comes to the brain from a different perspective.
In Do No Harm, an award-winning account of his work, Marsh writes that, as he begins to operate, “mind” and “brain” intersect. He says the idea that his instruments are “moving through thought itself, through emotion and reason, and that memories, dreams and reflections should consist of jelly, is simply too strange to understand. All I can see in front of me is matter.”
The neurons of this “grey matter”, according to Lees, “form part of a kaleidoscopic internet. On its own, a nerve cell is no more effective than an isolated termite worker, but through a sophisticated lattice of nerve stations it creates unique trails that together produce a cosmic highway. No single nerve cell is separated from any other by more than six neurons.” Brains, however, nurture an awful lot of neurons. In an ordinary brain, for instance, there are about 20bn neurons and each one makes on average 10,000 connections. The extraordinary computational power of a healthy brain holds the key to our lives as human beings.
To put this another way, if you could somehow connect all the laptop computers of London or New York, you would only just begin to equal the capacity of a single brain. This analogy comes from Dr Richard Frackowiak, formerly of the Wellcome Institute, which faces the National Hospital from the opposite side of Queen Square. Frackowiak also describes the brain as “an organ in a box (the skull) with a hole at the bottom where the brain stem is situated”. Such an oversimplification is a provocative response to a profound mystery. The working of the brain is so complex that even the experts still resort to metaphor to convey its functions, a response that’s as old as Aristotle. For the Greeks, the brain’s function was to cool the blood. For Descartes, in the 17th century, the brain was comparable to the latest, dazzling artistic technology, the hydrostatic fountains of Versailles.
After the industrial revolution, doctors revised this metaphor still further, establishing an orthodoxy that persisted to the end of the last century. To the Victorians, therefore, cerebral activity was analagous to the latest technology. The pathways of the brain were seen as fixed and rigid, like a railway network, and later as a telephone exchange. We, in the computer age, have found other ways to describe the working of the brain, derived from computer science, the phenomenon known as “plasticity”.
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